Scientists have grown fully mature brain cells in a laboratory for the first time, using a technique that mimics the natural process of brain regeneration.

It promises to open the door to new ways of treating and possibly curing debilitating brain diseases such as Parkinson's, epilepsy and Alzheimer's.

The scientists said they were able to produce virtually unlimited quantities of brains cells, which could revolutionise transplant medicine as well as leading to new drugs to stimulate the regrowth of damaged nerves.

Bjorn Scheffler, a neuroscientist at Florida University who made the breakthrough, said the procedure involved mimicking the natural process through which key stem cells in the brain orchestrate partial regeneration of the brain.

"Our study shows for the first time the entire process that goes on in our brain for life. We can, in a dish, recapture the process in front of our eyes," Dr Scheffler said. It was not the first time that scientists had shown stem cells can be manipulated in the lab to produce mature brain cells, he added. "But nobody has been capable of replicating the process from the very first step to the very last step - it's unique to get the whole process happening before your eyes."

The study, published in the journal Proceedings of the National Academy of Sciences, was done with mice but the scientists believe it is only a matter to time before they are able to reproduce the same process of development with human brain cells.

The findings, in effect, show it is possible to construct an assembly line for manufacturing unlimited quantities of human brain cells, or neurons, Dr Scheffler said. "We can basically take these cells and freeze them until we need them. Then we thaw them, begin a cell-generating process and produce a ton of new neurons."

Professor Dennis Steindler, who led the Florida research team, said the strength of the technique lay in its ability to identify vital stem cells that have the power to grow into adult brain cells.

"We've isolated for the first time what appears to be the true candidate stem cell," Professor Steindler said. "There have been other candidates but, in this case, we used a special microscope that allows us to watch living cells over long periods of time.

"So we've actually witnessed the stem cell give rise to new neurons. We've watched it under a living microscope generate brand new neurons.

"For many years, different groups - including mine - have claimed we're getting close to identifying the true stem cell progenitor, characterising it and watching its magic.

"What we've learnt from the 50 years of research into bone marrow and blood stem cells is to be extremely careful in claiming we've got the mother of all stem cells in adult brain tissue," he said.

Time-lapse images taken by the scientists show how simple, immature stem cells gradually develop and grow into the fully functioning cell - vital to the healthy functioning of the brain.

"Now we can make a lot of brain cells from just a very small number of these stem cells, which is great because we'd have to do that to repair neurological disease," Professor Steindler said.

Another possibility is to use the technique as a model of natural brain repair so that scientists can test potential drugs for stimulating the regrowth of damaged nerves.

"We are already beginning the process of screening for compounds that will allow this to happen perhaps without sticking anything into our brains," Professor Steindler said.

"It's been the goal of this field of stem cell biology and regenerative medicine to get us closer to being able to pop a pill in your mouth when you have a neurological disorder that has a specific action on your own indigenous stem cell population.

"This is getting us one step closer to that because we can now produce large quantities of brain cells at will and we can now manipulate them in the laboratory.

"The home run is that we will find drugs to mobilise our own population [of brain stem cells], which is what this study is focusing on.

"I'm quite optimistic we will translate this to human therapeutics in the very near future," he added. "Because advances in the field of regenerative medicine are occurring so quickly at the moment, it could be anytime. It could be next week, it could be ten years. I'd like it to be next week."

Hopes for cure

Dementia

In Alzheimer's disease parts of the brain degenerate, leading first to loss of memory and later to loss of personality. Abnormal tissues called senile plaques and tangles appear in the brain.

There are few treatments available though some drugs can slow progression of the disease by a few months in some people. A treatment that halted the destruction of brain cells or led to their regeneration would bring new hope to millions of sufferers.

Parkinson's disease

This is a slowly progressing degenerative disorder of the nervous system which causes tremor, delayed movements and rigidity. Its cause lies deep within the brain, in an area called the basal ganglia. Treatment is with a variety of drugs, including levodopa and bromocriptine, but they do not cure or halt the progression of the disease though they make movement easier.

Epilepsy

Anything that irritates the brain can cause a seizure, such as lack of oxygen or a fever. In epilepsy even a minor stimulus may be enough - flashing lights, video games or even touching parts of the body. Repeated seizures caused by abnormal electrical activity in the brain is epilepsy. Drugs can usually control the seizures, but in 10 to 20 per cent of patients surgery has to be considered.